Figure 2. Nitrite and nitrosothiol (SNO) contents in grey poplar leaves upon acute ozone exposure (grey bars) compared to controls (black bars).

Poplar plants were fumigated with ozone and harvested immediately after ozone treatment. 200 µg homogenized plant material was mixed with 600 µl PBS buffer containing NEM and EDTA. For nitrite and SNO determination, 100 µl and 200 µl of the plant extracts were, respectively, injected into the reaction vessel of Sievers NO analyzer containing the reducing agent tri-iodide. To measure SNO, the plant extracts were pre-treated with sulfanilamide to chemically remove nitrite. Values represent means ± SE of 3 biological replicates measured in three independent analyses. *P<0.05 (Student’s t-test).